A method for improving die area and power efficiency in high dynamic range digital microphones

ABSTRACT

Exemplary multipath digital microphones described herein can comprise exemplary embodiments of automatic gain control and multipath digital audio signal digital signal processing chains, which allow low power and die size to be achieved as described herein, while still providing a high DR digital microphone systems. Further non-limiting embodiments can facilitate switching between multipath digital audio signal digital signal processing chains while minimizing audible artifacts associated with either the change in the gain automatic gain control amplifiers switching between multipath digital audio signal digital signal processing chains.

PRIORITY CLAIM

This patent application is a Continuation Application that claimspriority to U.S. patent application Ser. No. 16/938,734, filed Jul. 24,2020, entitled “A METHOD FOR IMPROVING DIE AREA AND POWER EFFICIENCY INHIGH DYNAMIC RANGE DIGITAL MICROPHONES,” which patent application is aContinuation Application that claims priority to U.S. patent applicationSer. No. 16/543,276, filed Aug. 16, 2019, entitled “A METHOD FORIMPROVING DIE AREA AND POWER EFFICIENCY IN HIGH DYNAMIC RANGE DIGITALMICROPHONES,” which is a Non-Provisional application that claimspriority to U.S. Provisional Patent Application Ser. No. 62/765,085,filed Aug. 17, 2018, entitled “A METHOD FOR IMPROVING DIE AREA AND POWEREFFICIENCY IN HIGH DYNAMIC RANGE DIGITAL MICROPHONES,” the entirety ofwhich application are incorporated by reference herein.

TECHNICAL FIELD

The subject disclosure relates to digital microphones and, morespecifically, to multipath digital microphone implementations.

BACKGROUND

Microphones can be exposed to environments where sound levels, describedon a log scale using units of decibels of sound pressure level (dB SPL),can range from very quiet (e.g., less than 25 dB SPL) to very loud(e.g., 140 dB SPL). In addition, microphones are typically required tomaintain their performance over a large signal range, e.g., up to 120dB. Simultaneously, microphones are required to exhibit very smallintrinsic noise in order to make weak audio signals detectable, whilethey also need to handle very large audio signals without significantdistortion. As a result, such requirements dictate that microphones havea very large dynamic range (DR).

Analog and digital microphones output a voltage or digital outputstream, respectively, corresponding to the audio signal sensed by themicrophone. The advantage of a digital microphone is that its digitaloutput stream is relatively immune to noise and that ananalog-to-digital converter (ADC) is not required to perform digitalsignal processing on the microphone digital output stream. However, onedisadvantage of a digital microphone is that its dynamic range is oftenlower than what can be achieved with an analog microphone due toconstraints in the power consumption and or die size or area that can beallocated to the microphone within many applications.

Conventional solutions for improving DR of a digital microphone caninclude techniques such as employing one or more of a high DR ADC oremploying an automatic gain control amplifier (AGC) which cansignificantly lower ADC DR requirements while still meeting the desiredmax SPL and noise floor levels of the overall digital microphone.However, such conventional solutions can require excessively large powerconsumption, die area, and/or introduce troublesome artifacts.

In addition, the ability to integrate a high DR digital microphone isdesirable for implementation in devices such as mobile devices that canbe exposed to a variety of widely varying SPL environments. For example,a digital microphone comprising one or more microelectromechanicalsystems (MEMS) acoustic sensors with a component implementing analgorithm for high DR in complementary metal oxide semiconductor (CMOS)processes can provide a low power, high DR digital microphone suitablefor such mobile devices. However, as the demands for consumerelectronics trends toward smaller, mobile, and more feature-richdevices, the need for a high DR, digital, feature-rich microphonecontinues to confront continued demand for smaller and more powerefficient devices. Thus, a low-power, compact, high DR digitalmicrophone digital microphone remains a challenge.

It is thus desired to provide high dynamic range digital microphonesthat improve upon these and other deficiencies. The above-describeddeficiencies are merely intended to provide an overview of some of theproblems of conventional implementations, and are not intended to beexhaustive. Other problems with conventional implementations andtechniques, and corresponding benefits of the various aspects describedherein, may become further apparent upon review of the followingdescription.

SUMMARY

The following presents a simplified summary of the specification toprovide a basic understanding of some aspects of the specification. Thissummary is not an extensive overview of the specification. It isintended to neither identify key or critical elements of thespecification nor delineate any scope particular to any embodiments ofthe specification, or any scope of the claims. Its sole purpose is topresent some concepts of the specification in a simplified form as aprelude to the more detailed description that is presented later.

In a non-limiting example, an exemplary multipath digital microphone isdescribed. The exemplary multipath digital microphone described hereincan comprise exemplary embodiments of multipath digital microphonesemploying automatic gain control, which allow low power and die area tobe achieved for amplifiers or gain stages in exemplary multipath digitalmicrophone arrangements described herein, while still providing high DRdigital microphone systems. Exemplary multipath digital microphonesdescribed herein can comprise exemplary embodiments of automatic gaincontrol and multipath digital audio signal digital signal processingchains, which allow low power and die size to be achieved as describedherein, while still providing a high DR digital microphone systems.Further non-limiting embodiments can facilitate switching betweenmultipath digital audio signal digital signal processing chains whileminimizing audible artifacts associated with either the change in thegain automatic gain control amplifiers switching between multipathdigital audio signal digital signal processing chains

Accordingly, an exemplary multipath digital microphone can comprise anautomatic gain control (AGC) component configured to determine andadjust gain for each of a plurality of amplifiers based at least in parton a characteristic measurement of an associated audio signal in themultipath digital audio signal digital signal processing chains.Furthermore, exemplary multipath digital microphone systems can comprisea multipath digital audio combiner component comprising a multiplexingcomponent configured to switch from conveying one corrected digitalaudio signal to conveying a second corrected digital audio, afterperforming gain and/or offset correction to provide the correcteddigital audio signals.

In a further non-limiting aspect, exemplary methods and systemsassociated with multipath digital microphone systems are described.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Various non-limiting embodiments are further described with reference tothe accompanying drawings, in which:

FIG. 1 depicts a functional block diagram of an exemplary operatingenvironment suitable for incorporation of various non-limiting aspectsof the subject disclosure;

FIG. 2 depicts another exemplary operating environment illustratingnon-limiting aspects of the disclosed subject matter;

FIG. 3 depicts a non-limiting block diagram of exemplary aspects of anembodiment of automatic gain control, according to various embodimentsdescribed herein;

FIG. 4 depicts a non-limiting block diagram of exemplary aspects ofmultipath digital signal processing signal chain, according to variousnon-limiting embodiments;

FIG. 5 depicts a non-limiting block diagram of exemplary aspects ofautomatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains, according to various non-limitingembodiments;

FIG. 6 depicts a non-limiting block diagram of exemplary aspects ofautomatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains, according to various non-limitingembodiments;

FIG. 7 depicts another non-limiting block diagram of exemplary aspectsof automatic gain control in an exemplary embodiment of multipathdigital signal processing signal chains, according to variousnon-limiting embodiments;

FIG. 8 depicts an exemplary flowchart illustrating non-limiting aspectsof automatic gain control in an exemplary embodiment of multipathdigital signal processing signal chains, according to variousnon-limiting embodiments; and

FIG. 9 depicts an exemplary flowchart of non-limiting methods associatedwith a various non-limiting embodiments of the subject disclosure.

DETAILED DESCRIPTION

While a brief overview is provided, certain aspects of the subjectdisclosure are described or depicted herein for the purposes ofillustration and not limitation. Thus, variations of the disclosedembodiments as suggested by the disclosed apparatuses, systems, andmethodologies are intended to be encompassed within the scope of thesubject matter disclosed herein.

According to various described embodiments, the subject disclosureprovides digital microphones, systems, and methods for multipath digitalmicrophones. For instance, as described above, a digital microphoneoutputs a digital output signal corresponding to an audio signal sensedby the microphone. While a digital microphone is relatively immune tonoise and does not require an ADC on its output stream, the dynamicrange can be lower than what can be achieved with an analog microphoneunless constraints in the microphone power consumption for particularapplications can be met. As the demands for consumer electronics trendstoward smaller, mobile and more feature-rich devices, the need for ahigh DR, digital, feature-rich microphone continues to confrontcontinued demand for smaller and more power efficient devices.

FIG. 1 depicts a functional block diagram of an exemplary operatingenvironment 100 suitable for incorporation of various non-limitingaspects of the subject disclosure. As a non-limiting example, anexemplary operating environment 100 can comprise one or more exemplarymicroelectromechanical systems (MEMS) acoustic or microphone sensors 102(e.g., one or more of MEMS acoustic or microphone sensor, etc.). Invarious embodiments, exemplary systems are depicted as comprising oneMEMS acoustic or microphone sensor 102, whereas other exemplary systemscan be described as comprising more than one MEMS acoustic or microphonesensors 102. It can be appreciated that the various MEMS acoustic ormicrophone sensors 102 need not be identical in design, fabrication,characteristic, and/or placement, etc., and according to a non-limitingaspect, the one or more exemplary MEMS acoustic or microphone sensors102 vary in one or more of the forgoing aspects. In a non-limitingaspect, the one or more of MEMS acoustic or microphone sensors 102 canbe configured to receive one or more of the acoustic signal or avariation associated with the acoustic signal (e.g., such as theacoustic signal varied by differences in time, location, acoustic path,etc.) or can be comprised of any number of disparate transducerstructures (e.g., numbers and/or configuration of membranes, etc.), anynumber of front end circuit designs (e.g., supplying variable chargepump voltages, etc.), etc., for example.

The one or more MEMS acoustic or microphone sensors 102 can beconfigured to receive one or more acoustic signals, and can beoperatively coupled to one or more components or circuitry 104 (e.g.,one or more components or circuitry 104, etc., sometimes referred to,herein, as, “front end”) configured to process one or more electricalsignals (e.g., one or more electrical signals associated with one ormore of MEMS acoustic or microphone sensor, etc.) that vary inaccordance with the one or more acoustic signals to create one or morecorresponding processed electrical signal (e.g., at one or more outputsof the one or more components or circuitry 104, etc.).

In a further non-limiting example, an exemplary operating environment100 can comprise one or more exemplary amplifier or gain stage 106(e.g., one or more amplifier or gain stage 106, etc.) operativelycoupled to the one or more output associated with the one or morecomponents or circuitry 104 (e.g., one or more of components orcircuitry 104, etc.). In a non-limiting aspect, the one or moreamplifier or gain stage 106 can be configured to receive the one or morecorresponding processed electrical signals and/or apply one or morescaling factors (e.g., one or more analog scaling factors) to the one ormore corresponding processed electrical signals via an exemplaryautomatic gain control (AGC) component (not shown), for example, asfurther described herein, regarding FIGS. 2-9 .

In addition, exemplary operating environment 100 can further compriseone or more exemplary ADCs 108 operatively coupled to one or moreoutputs associated with the one or more amplifier or gain stage 106, asfurther described herein, regarding FIGS. 2-9 . In another non-limitingaspect, the one or more exemplary ADCs 108 can be configured to provideone or more digital audio signals having different digital scalingfactors associated with the one or more acoustic signals (e.g., atoutputs associated with the one or more ADCs 108, etc.). In a furthernon-limiting aspect, the one or more components or circuitry 104 cancomprise or be associated with one or more adjustable direct current(DC) bias voltage circuit operatively coupled to the one or more of MEMSacoustic or microphone sensors 102 and can be configured to adjust oneor more DC bias voltage provided to the one or more of MEMS acoustic ormicrophone sensors 102, respectively, e.g., via one or more charge pump110.

FIG. 2 depicts another exemplary operating environment 200 illustratingnon-limiting aspects of the disclosed subject matter. Accordingly,exemplary operating environment 200 can comprise signal processingblocks of a typical application specific integrated circuit (ASIC) for adigital microphone, and can typically comprise input buffer A0 202,amplifier, gain stage or preamp A1 204, anti-aliasing filter (AAF) 206,an ADC 108 such as a delta-sigma modulator (DSM) 208, and decimationfilter (DEC) 210. In a non-limiting aspect, exemplary input buffer A0202 can be an input buffer or impedance converter that converts the highimpedance or capacitance input from the MEMS microphone to a lowimpedance output. In further non-limiting aspect, exemplaryanti-aliasing filter 206 can comprise a filter (e.g., a low pass filter,a decimation filter, etc.) to remove frequencies that are too close tosampling frequency of the ADC, e.g., delta-sigma modulator 208.

Specifications for low noise, high signal to noise ratio (SNR), acousticoverload point AOP and so on drive designs to limit power and space,while still providing high performance digital microphones, as furtherdescribed herein. For example, to improve noise or SNR of the digitalmicrophone by 6 decibel (dB), or a factor of two, the power consumptionand area of blocks in the signal chain are increased by a factor offour. As another non-limiting example, sacrifices in area of theanti-aliasing filter 206 and area and power in the ADC 108 such as adelta-sigma modulator 208 requires a gain as high as possible gain ofamplifier, gain stage or preamp A1 204, which can reduce the acousticoverload point (AOP).

Similarly, in order to improve dynamic range without the negativeeffects of increasing supply current, power consumption, or area,various embodiments described herein can employ adjustment of the gainin accordance with signal levels, rather than employing simple linearprocessing in the signal chain. Two conventional approaches haveemployed either AGC or multipath digital signal processing signalchains, each with their attendant drawbacks.

Accordingly, in various non-limiting embodiments, automatic gain control(AGC) and multipath digital signal processing can be employed to providehigh performance digital microphones without the negative impacts on diearea and power consumption, as described above. In a non-limitingaspect, one signal path in a multipath digital signal processing signalchain can be employed to process low sound pressure level (SPL) signals(e.g., higher gain in A1 204), whereas another signal path in themultipath digital signal processing signal chain can be employed toprocess high sound pressure level signals (e.g., lower gain in A1 204).In further non-limiting aspects, it can be understood that, higher gainin A1 204 in the low sound pressure level digital signal processingsignal chain can relax the design specifications (e.g., allowing forlower power and area) in an exemplary ADC such as a delta-sigmamodulator (DSM) 208 and AAF 206 in the low sound pressure level digitalsignal processing signal chain, whereas the lower gain in A1 in the highsound pressure level digital signal processing signal chain can resultin higher noise in the high sound pressure level digital signalprocessing signal chain, but with the ability to provide a moreefficient high performance digital microphone without the negativeimpacts on die area and power consumption.

Thus, it can be understood that in power and size optimized linear highdynamic range systems, any further improvement of dynamic range requiresa corresponding increase of power consumption, where improved dynamicrange of digital microphones can employ multi-path signal processing andincreasing power supply for blocks processing high dynamic rangesignals. To make the power supply and occupied die area less dependenton the dynamic range, non-linear signal processing, such as multipath orautomatic gain control systems can be implemented, where the largest andmost power consuming blocks (e.g., filters, ADCs, etc.) process a signalwith much less dynamic range than required by the application, thus,saving a substantial amount of die area and power. Multipath signalprocessing may require more chip area and power consumption, and asfurther described herein. On the other hand, AGC methods typicallyrequire less area and power, but their usage is limited to high soundpressure levels, where the sound masks audible artifacts, such asharmonic distortion caused by non-linear signal processing and non-idealmatching of analog and digital signal processing block counterparts, orglitches during gain switching caused by non-infinite bandwidth,mismatches of gains and DC offsets or just a too large difference ofnoise levels, so that these artifacts become inaudible for humanhearing.

As described, in low noise digital microphones, the largest and mostpower consuming blocks are typically filters and ADCs. Accordingly,various embodiments as described herein can be configured to amplify thesignal in front of these blocks as much as possible and attenuate itafter them. For instance, by combining multipath digital signalprocessing signal chain employing automatic gain control at the gainstages, solutions can be designed that take advantages of the benefitsof both, while minimizing the negative impacts of either.

FIG. 3 depicts a non-limiting block diagram 300 of exemplary aspects ofan embodiment of automatic gain control, according to variousembodiments described herein. For example, as described above regardingFIG. 1 , one or more exemplary MEMS acoustic or microphone sensors 102can be operatively coupled to one or more components or circuitry 104 orfront end. The one or more exemplary MEMS acoustic or microphone sensors102 can be operatively coupled to a respective gain stage or preamp A1204 comprising automatic gain controlled gain stage or preamp 302, whichgain can be adjusted, in a non-limiting example by varying theresistance (e.g., of a switched resistor network (not shown) variableresistor R₂ 304. In further non-limiting aspect, output of gain stage orpreamp A1 204 comprising automatic gain controlled gain stage or preamp302 can be processed according to the embodiment described in FIG. 2(e.g., AAF and ADC 306), and further digital signal processing 308(e.g., digital gain compensation, etc.), or as further described herein.

As can be seen in FIG. 3 , some benefits of employing automatic gaincontrol can include the simplicity of design of a single channel orsignal processing chain, which requires only one preamp or gain stageand one ADC, which allows higher gain before ADC 108 such as DSM 208, sothat lower ADC noise can be achieved. This further allows for dramaticpower reduction (e.g., lower supply current) of the ADC and allows forlower die area. In addition, various embodiments employing automaticgain control can allow for ease of digital gain compensation. However,at gain transitions, potential glitches can arise. For instance, audibleglitches can arise due to one or more of mismatches between analog anddigital gain, difficulties in analog offset compensation, and/or thefinite bandwidth of analog signal processing blocks that limits how fastanalog and digital blocks can react to gain switches in the system. Inaddition, preamp or gain stage power can be relatively high.

Thus, in further non-limiting aspects, various embodiments describedherein can employ small gain steps of approximately 6 dB in AGC gaintransitions such that digital gain compensation can mitigate oreliminate potential glitches.

FIG. 4 depicts a non-limiting block diagram 400 of exemplary aspects ofmultipath digital signal processing signal chain, according to variousnon-limiting embodiment. U.S. Pat. No. 9,673,768 describes multipathdigital microphone systems comprising a multipath digital audio combinercomponent, the entirety of which is herein incorporated by reference. Asa non-limiting example, FIG. 4 depicts a functional block diagram of anexemplary digital microphone system comprising a non-limitingimplementation of a two-path digital combiner audio combiner component402 according to aspects of the subject disclosure. For instance, asdescribed above regarding FIG. 1 , exemplary digital microphone systemcan comprise one or more exemplary MEMS acoustic or microphone sensors102 (e.g., one or more MEMS acoustic or microphone sensor 102, etc.),operatively coupled to one or more components or circuitry 104 (e.g.,one or more components or circuitry 104, etc.), or front end, one ormore exemplary amplifiers or gain stages 106 (e.g., one or more ofamplifiers or gain stages 106, etc.) operatively coupled to the one ormore output associated with the one or more components or circuitry 104(e.g., one or more components or circuitry 104, etc.), one or moreexemplary ADCs 108 (e.g., one or more ADC 108, etc.) operatively coupledto one or more outputs associated with the one or more amplifiers orgain stages 106. In addition, exemplary digital microphone system canfurther comprise an exemplary multipath digital audio combiner component402 operatively coupled to one or more outputs associated with the oneor more ADCs 108 (e.g., outputs associated with the one or more ADC 108,etc.). In addition, unlike in an AGC approach (e.g., adjusting analogscaling factors prior to the ADC), these gain values, K_(HI) andK_(LO)), are described in U.S. Pat. No. 9,673,768 as nominally staticrather than varying according to the input signal levels (though theirvalues may be changed under different operating modes of the digitalmicrophone), in a further non-limiting aspect. For instance, rather thanchanging a gain value according to the input audio signal level as donein AGC systems, an exemplary multipath digital audio combiner component210, as described in U.S. Pat. No. 9,673,768, can be configured toselect an ADC output from the Low SPL path or the High SPL pathaccording to an input audio signal level.

As a further non-limiting example, for small input audio signal levels,the Low SPL path output can be chosen (e.g., by exemplary multipathdigital audio combiner component 402 or portions thereof) for output toexemplary path combiner output, out[k], but when the input audio signallevel is close to exceeding the Max SPL range of the Low SPL path,exemplary multipath digital audio combiner component 402 can be furtherconfigured to select the High SPL path for output to exemplary pathcombiner output, out[k].

In the non-limiting example shown in FIG. 4 , it is assumed that theHigh SPL path ADC (e.g., corresponding to exemplary ADC 208 as describedin FIG. 2 ) is designed to have worse noise than the Low SPL path ADC(e.g., exemplary ADC 206), which allows the High SPL path ADC (e.g.,corresponding to exemplary ADC 208 as described in FIG. 2 ) to beimplemented with significantly lower power consumption than the Low SPLpath ADC (e.g., corresponding to exemplary ADC 206 as described in FIG.2 ). However, due to the higher ADC noise and reduced amplifier gain inthe High SPL path (e.g., corresponding to exemplary ADC 206 as describedin FIG. 2 ), the noise floor increases when sending the High SPL path(e.g., corresponding to exemplary amplifier or gain stage 204 andexemplary ADC 208 as described in FIG. 2 ) to the overall microphoneoutput (e.g., exemplary path combiner output, out[k]) rather than theLow SPL path Low SPL path (e.g., corresponding to another exemplaryamplifier or gain stage 202 and exemplary ADC 206 as described in FIG. 2). It can be understood that this increase in noise floor will beacceptable for many audio applications since the High SPL path (e.g.,corresponding to exemplary amplifier or gain stage 204 and exemplary ADC208 as described in FIG. 2 ) is only activated when large audio signalsoccur. Thus, the overall digital microphone as depicted regardingexemplary digital microphone system is able to achieve a large DRwithout requiring a large DR ADC, which, in turn, enables a relativelylow power digital microphone implementation that can achieve similar DR,for example, as an analog microphone as described in U.S. Pat. No.9,673,768.

For instance, as described above, exemplary digital microphone system ofFIG. 4 is depicted as digital two-path microphone system that can employa single MEMS acoustic or microphone sensor 102 and a single front end104 coupled to a Low SPL path (e.g., comprising exemplarypreamplifier/gain stage 404 and exemplary ADC 408) and a High SPL path(e.g., comprising exemplary preamplifier/gain stage 406 and exemplaryADC 410), with the outputs of exemplary ADC 408 and ADC 410 coupled toexemplary multipath digital audio combiner component 402, which providesan exemplary path combiner output, out[k].

In a non-limiting aspect, exemplary digital microphone system cancomprise exemplary ADC 408 and ADC 410 employing a Delta-Sigma (Δ-Σ)architecture, in which the sample rate of the ADC is much higher thanthe bandwidth of the audio signal, and in which a significant amount ofhigh frequency quantization noise can be present in the ADC output(e.g., output of exemplary ADC 408 and ADC 410). As further describedabove, exemplary multipath digital audio combiner component 402 cancomprise one or more of digital audio filters 202 (e.g., one or more ofdigital audio filters 206 a, 206 b, . . . , 206 n, etc.) operativelycoupled to one or more exemplary ADCs 108 (e.g., one or more of ADC 108a, 108 b, . . . , 108 n, etc., such as DSM 208). As described herein,the one or more of digital audio filters 206 can be configured toreceive one or more of digital audio signals having different scalingfactors of an associated audio signal and can be configured to provideone or more of filtered digital audio signals, as described herein.Accordingly, in a further non-limiting aspect, the one or more ofdigital audio filters 206 can comprise one or more decimators 412 (e.g.,decimator 412 a, 412 b, etc.). Thus, exemplary digital microphone systemcomprising an exemplary multipath digital audio combiner component 402can comprise one or more exemplary decimators 412 (e.g., decimator 412a, 412 b, etc.) configured to reduce the impact of Δ-Σ quantizationnoise. In further non-limiting aspect, the one or more exemplarydecimators 412 (e.g., decimator 412 a, 412 b, etc.) can also lower theclock rate of path combine digital circuits associated with exemplarymultipath digital audio combiner component 402. As a result, outputs ofexemplary ADC 408 and ADC 410 can be decimated to produce signalsin_lo_raw[k] (414) and in_hi_raw[k] (416) as indicated in FIG. 4 .

As further described in U.S. Pat. No. 9,673,768, exemplary multipathdigital audio combiner component 402 can comprise an exemplary gain andoffset estimation component 418 that can be configured to estimate oneor more of gain differences or offset differences between the one ormore filtered digital audio signals. In a non-limiting aspect, exemplarymultipath digital audio combiner component 402 can be configured toemploy the one or more of gain differences or offset differences toscale one or more of the one or more of filtered digital audio signalsto provide a scaled digital audio signal, and can be configured toadjust offset associated with the one or more of filtered digital audiosignals. As a non-limiting example, exemplary gain and offset estimationcomponent 418 can be configured to utilize information in in_lo_raw[k](414) and in_hi_raw[k] (416) to estimate the gain and/or offsetdifferences between each of these signals (e.g., in_lo_raw[k] (414) andin_hi_raw[k] (416)). In a further non-limiting aspect, a gain differenceestimate can be employed to form a gain_hi[k] (420) signal to facilitatescaling the in_hi_raw[k] signal (416), with the resultingin_hi_scaled[k] (422) signal then having a matched scale factor to thein_lo_raw[k] (414) signal. While for purposes of illustration, FIG. 4 isshown as facilitating the scaling the in_hi_raw[k] signal (416), inother non-limiting implementations, a scale factor can be appliedin_lo_raw[k] (414) instead of or in addition to applying the scalefactor gain_hi[k] (420) to the in_hi_raw[k] (416) signal.

In yet another non-limiting aspect, in addition to gain estimation,exemplary gain and offset estimation component 418 can be configured toutilize information in in_lo_raw[k] (414) and in_hi_raw[k] (416) tofacilitate estimating offset differences, to facilitate addingoffset_lo[k] (424) to in_lo_raw[k] (414) and facilitate addingoffset_hi[k] (426) to in_hi_scaled[k] (422). It can be understood thatexemplary offset_lo[k] (424) and exemplary offset_hi[k] (426) signalscan be configured to correct for offset differences between the High SPLpath (e.g., comprising exemplary preamplifier/gain stage 406 andexemplary ADC 410) and Low SPL path (e.g., comprising exemplarypreamplifier/gain stage 404 and exemplary ADC 408), for example, duringtimes that exemplary multipath digital audio combiner component 402switches exemplary path combiner output, out[k], from conveying one ofone or more of corrected digital audio signals (e.g., one of in_lo[k](428) or in_hi[k] (430)) to conveying a second one of the one or more ofcorrected digital audio signals (e.g., the other of in_lo[k] (428) orin_hi[k] (430)).

For example, as further described in U.S. Pat. No. 9,673,768, forexample, an exemplary MUX component 432 can be configured to switch fromconveying one of one or more of corrected and/or scaled digital audiosignals (e.g., one of in_lo[k] (428) or in_hi[k] (430)) to conveying asecond one of the one or more of corrected digital audio signals (e.g.,the other of in_lo[k] (428) or in_hi[k] (430)) based on one or moreswitching criteria determined by an exemplary multipath digital audiocombiner component 402, for example, as further described below. As anon-limiting example, an exemplary MUX component 432 can be configuredto switch from conveying one of one or more of corrected or scaleddigital audio signals to conveying a second one of the one or more ofcorrected or scaled digital audio signals based on switching criteriacomprising or associated with amplitude measurement, absolute value ofthe amplitude measurement, root-mean-square power measurement ofdigitized data associated with the one or more digital audio signals orone or more of the digital audio signals having a characteristicmeasurement above a threshold, for example, as further described herein.Accordingly, exemplary path combiner component output, out[k], can beswitched from conveying one of one or more of corrected or scaleddigital audio signals (e.g., one of in_lo[k] (428) or in_hi[k] (430)) toconveying a second one of the one or more of corrected digital audiosignals (e.g., the other of in_lo[k] (428) or in_hi[k] (430)) (e.g.,switched from the Low SPL path, comprising exemplary preamplifier/gainstage 404 and exemplary ADC 408, to the High SPL path, comprisingexemplary preamplifier/gain stage 406 and exemplary ADC 410), viaexemplary MUX component 432 that is fed by the gain and offset correctedsignals for each path, in_lo[k] (428) and in_hi[k] (430), and controlledby an exemplary in_hi_selected[k] signal (434). The details of how thein_hi_selected (434) signal is determined are further described in U.S.Pat. No. 9,673,768. However, according to further non-limiting aspects,non-limiting details of how exemplary MUX component 432 can beconfigured to be switched from conveying one of one or more of correctedor scaled digital audio signals (e.g., one of in_lo[k] (428) or in_hi[k](430)) to conveying a second one of the one or more of corrected digitalaudio signals (e.g., the other of in_lo[k] (428) or in_hi[k] (430))(e.g., switched from the Low SPL path, comprising exemplarypreamplifier/gain stage 404 and exemplary ADC 408, to the High SPL path,comprising exemplary preamplifier/gain stage 406 and exemplary ADC 410),via exemplary MUX component 432 in the context of various disclosedembodiments is described below regarding FIG. 8 .

As can be seen in FIG. 4 , some benefits of employing multipath digitalsignal processing signal chains can include switching done completely inthe digital domain, allowance of gain error correction and/or offsetequalization, which allow for continuous calibration of gain/offsetbetween paths to avoid artifacts, detection of zero crossing ifdesirable to facilitate switching with no glitches due to difference insignals, and if employing a capacitive based amplifier for a constantgain in preamp gain stage, further increases in power efficiency.However, it can be understood from FIG. 3 that employing multipathdigital signal processing signal chains can comprise two or more signalpaths, gain stages, and ADCs, larger die area and higher supply current,which can be mitigated by reduced noise requirements in the high SPLpath, differences in noise levels in the signal paths which can resultin audible artifacts when switching, if signal is not much higher thannoise, and channel switching point limited (e.g., min. ˜110 dB SPL) as aresult of the increased gain in the low sound pressure level path andhigher sensitivity of undesired signals (e.g., ultrasonic signals)activating high SPL Path with higher noise.

Thus, as described in FIG. 4 an exemplary dual-path system has proven toprovide a very good and non-audible switching between the signal paths,if the signal magnitude and offset can be fully post-processed andcontrolled in the digital domain. The limiting factor for setting theswitching threshold can be understood to be the difference in noiselevels between the two signal paths (e.g., Low SPL path and High SPLpath). For instance, if the signal level between the two paths isapproximately 20 dB, then the noise levels between the two paths may beapart by approximately 20 dB. As described above, an AGC system can beconfigured to switch gain in lower steps (e.g., approximately 6 dB,etc.). This can be understood to imply that the difference in noiselevels is much less significant as well. However, as further describedabove, the single path nature of the AGC based system does not allow tofully process and control the signal differences in the digital domain,thus small differences in signal magnitudes and offsets will be present,causing audible artifacts, that are very costly to remove in terms ofchip area and power consumption.

Thus, according to various non-limiting embodiments, by combiningmultipath digital signal processing signal chain employing automaticgain control (AGC) at the gain stages, solutions can be designed thattake advantages of the benefits of both while minimizing the negativeimpacts of either. Accordingly, in non-limiting aspects, variousembodiments disclosed herein can employ a combination of multipathsignal processing chains and AGC signal processing, where the digitalsignal processing blocks can be configured to correct for the signalamplitude and offset difference between the two signal paths (e.g., LowSPL path and High SPL path), yet the gain and noise level differencesbetween the two paths can be kept very low (e.g., 6 dB), non-limitingaspects, in further, allowing to switch between the two paths at muchlower sound pressure levels without audible switching artifacts. In afurther non-limiting aspect, employing lower switching thresholds canfurther facilitate using filters and ADCs with significantly lowerdynamic range, thus, saving a substantial amount of die area andreducing power consumption.

FIG. 5 depicts a non-limiting block diagram 500 of exemplary aspects ofautomatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains, according to various non-limitingembodiments. Various non-limiting embodiments as described herein canemploy two or more signal paths (e.g., Low SPL path and High SPL path,etc.) that can comprise a low SPL AGC gain stage 502 and a high SPL AGCgain stage 504 as depicted in FIG. 5 and as further described hereinregarding FIG. 3 . In addition, further non-limiting embodiments asdescribed herein can further comprise respective ADCs associated withthe multipath digital signal processing signal chains (e.g., Low SPLpath and High SPL path, etc.) and further digital signal processing 506,for example, as further described herein, regarding FIG. 4 , or asfurther described below regarding FIGS. 6-8 .

Thus, FIG. 5 depicts a simplified non-limiting block diagram of anexemplary embodiment of multipath digital signal processing signal chainwith low and high SPL paths each employing exemplary aspects ofautomatic gain control, in further non-limiting aspects. A non-limitingembodiment can provide exemplary high performance digital microphoneshaving a low SPL path that can achieve required SNR at 94 dB, with AGCfunctionality in the low SPL path, which allows extra 6 dB of preampgain in low SPL path and dramatic power reduction in low SPL ADC, whileavoiding gain switching at SPL levels near 94 dB, and having a high SPLpath that can achieve high AOP that can be used when changing gain andat very high signal levels (e.g., above range of highest low SPL gainsetting), with AGC functionality in the high SPL path, which allowsmatching of highpass corners for low and high paths.

Thus, according to various non-limiting embodiments, by combiningmultipath digital signal processing signal chain employing automaticgain control at the gain stages, benefits of employing multipath digitalsignal processing signal chains with AGC can include switching donecompletely in the digital domain, allowance of gain error correctionand/or offset equalization, which allow for continuous calibration ofgain/offset between paths to avoid artifacts, detection of zero crossingif desirable to facilitate switching with no glitches due to differencein signals, employing small gain steps (e.g., 6 dB steps) in AGC gaintransitions such that digital gain compensation can mitigate oreliminate potential glitches, easy and fine digital gain adjustments,noise levels are ˜6 dB apart, resulting in no audible artifacts due tomuch lower switching thresholds. However, it can be understood thatcombining multipath digital signal processing signal chain employingautomatic gain control (AGC) at the gain stages can comprise two or moresignal paths, gain stages, and ADCs, larger die area and higher supplycurrent, which can be mitigated by channel switching point limited(e.g., below 100 dB SPL, 95 dB, etc.).

FIG. 6 depicts a non-limiting block diagram 600 of exemplary aspects ofautomatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains, according to various non-limitingembodiments. As non-limiting example, automatic gain control in anexemplary embodiment of multipath digital signal processing signalchains can comprise input buffer A0 202, for example, as described aboveregarding FIG. 2 . In a further non-limiting aspect, automatic gaincontrol in an exemplary embodiment of multipath digital signalprocessing signal chains can comprise a low SPL path comprisingamplifier, gain stage or preamp A1 602, anti-aliasing filter (AAF1) 604,an ADC 606 such as a delta-sigma modulator (DSM1) 606, and a decimationfilter (DEC1) 608, for example, as described above regarding FIG. 2 . Inanother non-limiting aspect, automatic gain control in an exemplaryembodiment of multipath digital signal processing signal chains cancomprise a high SPL path comprising amplifier, gain stage or preamp A2610, anti-aliasing filter (AAF2) 612, an ADC 614 such as a delta-sigmamodulator (DSM2) 614, and a decimation filter (DEC2) 616, for example,as described above regarding FIG. 2 . In yet another non-limitingaspect, amplifier, gain stage or preamp A1 602 and amplifier, gain stageor preamp A2 610 can be automatic gain controlled, for example, asfurther described above regarding FIGS. 3 and 5 , and as furtherdescribed herein.

Exemplary automatic gain control in an exemplary embodiment of multipathdigital signal processing signal chains can further comprise a gain andoffset estimation component 618, for example, as further described aboveregarding FIG. 4 , wherein an exemplary multipath digital audio combinercomponent can comprise one or more gain adjustment components 620, andone or more offset adjustment components 622, 624, that can beconfigured to perform one or more of gain and/or offset correction inthe multipath digital audio combiner component to provide a plurality ofcorrected digital audio signals (e.g., based in part on the gaindetermined by the AGC component). Automatic gain control in an exemplaryembodiment of multipath digital signal processing signal chains canfurther comprise a multiplexing component (e.g., MUX 626), for example,as further described, regarding FIG. 4 , that can be configured toswitch from conveying one of the corrected digital audio signals toconveying a second one of the corrected digital audio signals, e.g.,based on a comparison of a characteristic measurement of an audio signal(e.g., an audio signal in one or more of the signal processing chains)with a set of thresholds, for example, as further described herein,regarding FIG. 8 . In another non-limiting aspect, automatic gaincontrol in an exemplary embodiment of multipath digital signalprocessing signal chains can further comprise a multiplexing component(e.g., MUX 626), for example, as further described, regarding FIG. 4 ,that can be configured to switch from conveying one of the correcteddigital audio signals to conveying a second one of the corrected digitalaudio signals, e.g., based on a comparison of a characteristicmeasurement of an audio signal (e.g., an audio signal in one or more ofthe signal processing chains) with a gain associated one or moreattenuation components (not shown), in the signal processing chains, forexample, as further described herein, regarding FIG. 7 .

Automatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains can further comprise further digitalsignal processing components 628, e.g., such as decimators, reshapers,filters, and so on to provide a digital audio signal output, as furtherdescribed herein. In addition, in a further non-limiting aspect,automatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains can further comprise an exemplaryautomatic gain control component configured to determine and adjust gainfor each of the of amplifiers (e.g., amplifier, gain stage or preamp A1602 and amplifier, gain stage or preamp A2 610) based on acharacteristic measurement of the associated audio signal (e.g., anaudio signal in one or more of the signal processing chains), inpredetermined steps (e.g., 6 dB steps, etc.), for example, as furtherdescribed herein, regarding FIGS. 3 and 5 .

In a non-limiting example of automatic gain control in an exemplaryembodiment of multipath digital signal processing signal chains,amplifier, gain stage or preamp A1 602 can be configured to have gainvalues of 42, 30, 18, 6 dB, and amplifier, gain stage or preamp A2 610can be configured to have gain values of 36, 24, 12, 0 dB, wherein thelow SPL path 0 can be selected with amplifier, gain stage or preamp A1602 set to high gain (e.g., 42 dB), and wherein amplifier, gain stage orpreamp A2 610 can be set to 36 dB. As further described herein,regarding FIG. 8 , with increasing SPL, MUX 626 can be configured toswitch to high SPL path 1, with amplifier, gain stage or preamp A2 610gain set to 36 dB, and with amplifier, gain stage or preamp A1 602adjusting to 30 dB. With further increasing SPL, MUX 626 can beconfigured to switch back to low SPL path 0, with amplifier, gain stageor preamp A1 602 adjusted to 30 dB with amplifier, and gain stage orpreamp A2 610 gain adjusting to 24 dB. If the characteristic measurement(e.g., SPL) stays within the range, no change happens. Upon decreasingSPL, amplifier, gain stage or preamp A2 610 gain adjusts to 36 dB, MUX626 can be configured to switch back to high SPL path 1. If thecharacteristic measurement (e.g., SPL) stays within the range, no changehappens, in a further non-limiting aspect. With further decreasing SPL,MUX 626 can be configured to switch back to low SPL path 0, withamplifier, gain stage or preamp A1 602 adjusted to 42 dB with amplifier,and gain stage or preamp A2 610 gain set at 36 dB. This can be furtherunderstood by examination of the flowchart of FIG. 8 below.

FIG. 7 depicts another non-limiting block diagram 700 of exemplaryaspects of automatic gain control in an exemplary embodiment ofmultipath digital signal processing signal chains, according to variousnon-limiting embodiments. The description of components in FIG. 7 can bedescribed as above regarding FIG. 6 . Further non-limiting aspects ofautomatic gain control in an exemplary embodiment of multipath digitalsignal processing signal chains can be seen in FIG. 7 which can furthercomprise one or more exemplary attenuators D1 702 and D2 704. In anon-limiting aspect, an exemplary multipath digital audio combinercomponent, as described herein can further be configured to scale one ormore digital audio signals (e.g., at the output of decimation filter(DEC1) 608, decimation filter (DEC2) 612, etc.) via one or moreattenuation components D1 702 and D2 704, which can be configured toprovide a course digital gain adjustment, to provide a plurality ofscaled digital audio signals, e.g., based in part on the gain determinedby the AGC component 630 and/or one or more attenuation components D1702 and D2 704. In addition, an exemplary multipath digital audiocombiner component comprising one or more gain adjustment components 620can further provide a fine digital gain adjustment, to provide aplurality of scaled digital audio signals, e.g., based in part on thegain determined by the AGC component 630.

FIG. 8 depicts an exemplary flowchart 800 illustrating non-limitingaspects of automatic gain control in an exemplary embodiment ofmultipath digital signal processing signal chains, according to variousnon-limiting embodiments. For instance, as described above regardingFIG. 6 , in a non-limiting example of automatic gain control in anexemplary embodiment of multipath digital signal processing signalchains, amplifier, gain stage or preamp A1 602 can be configured to havegain values of 42, 30, 18, 6 dB, and amplifier, gain stage or preamp A2610 can be configured to have gain values of 36, 24, 12, 0 dB, whereinpath 0 can be selected with amplifier, gain stage or preamp A1 602 setto high gain (e.g., 42 dB), and wherein amplifier, gain stage or preampA2 610 can be set to 36 dB, at 802. As further described herein, withincreasing SPL (e.g., characteristic measurement greater than a highthreshold (804)), MUX 626 (at 806) can be configured to switch to path 1at 808, with amplifier, gain stage or preamp A2 610 gain set to 36 dB,and with amplifier, gain stage or preamp A1 602 adjusting to 30 dB, at810. With further increasing SPL, MUX 626 (at 806) can be configured toswitch back to path 0 (at 812), with amplifier, gain stage or preamp A1602 adjusted to 30 dB with amplifier, and gain stage or preamp A2 610gain adjusting to 24 dB (at 814). If the characteristic measurement(e.g., SPL) stays within the range, no change happens.

Upon decreasing SPL (e.g., characteristic measurement less than a lowthreshold (816)), then after a minimum decay time at 818, and with MUX626 at path 0 (at 820), amplifier, gain stage or preamp A2 610 gainadjusts to 36 dB (at 822), and MUX 626 can be configured to switch afterawaiting gain setting at 824, back to path 1, at 830. If thecharacteristic measurement (e.g., SPL) stays within the range, no changehappens, in a further non-limiting aspect. With further decreasing SPL,then after a minimum decay time at 818, and with MUX 626 at path 1 (at820), amplifier, gain stage or preamp A1 602 can be adjusted to 42 dB,and MUX 626 can be configured to switch after awaiting gain sitting at832 back to path 0, with amplifier, and gain stage or preamp A2 610 gainset at 36 dB.

Accordingly, various non-limiting embodiments of disclosed subjectmatter can provide systems, methods, and devices for automatic gaincontrol multipath digital audio signal processing chains.

Various non-limiting embodiments described herein can comprise amultipath digital audio combiner component that can be configured forautomatic gain control in multipath digital audio signal digital signalprocessing chains.

As a non-limiting example, an exemplary multipath digital audio combinercomponent can comprise one or more digital audio filters operativelycoupled to one or more ADCs and configured to receive one or moredigital audio signals having different scaling factors of an associatedaudio signal and configured to provide one or more filtered digitalaudio signals, in a non-limiting aspect. For instance, the exemplary oneor more digital audio filters comprise at least one of one or moredecimators or one or more low pass filters, as further described herein.

In a further non-limiting example, an exemplary multipath digital audiocombiner component can further comprise one or more amplifiersconfigured to generate one or more analog audio signals associated withthe one or more digital audio signals having different scaling factors,in another non-limiting aspect.

In addition, an exemplary multipath digital audio combiner component canfurther comprise an AGC component configured to determine and adjustgain for each of the one or more amplifiers based in part on acharacteristic measurement of the associated audio signal, as furtherdescribed herein. In a non-limiting example, an exemplary AGC componentcan be further configured to adjust gain for each of the one or moreamplifiers in predetermined gain steps, as further described herein. Ina further non-limiting aspect, exemplary AGC component can be furtherconfigured to adjust gain for each of the one or more amplifiers inpredetermined gain steps of approximately 6 dB gain steps.

In another non-limiting example, an exemplary multipath digital audiocombiner component can comprise a gain and offset estimation componentconfigured to estimate at least one of gain differences or offsetdifferences between the one or more filtered digital audio signals, inyet another non-limiting aspect. For instance, an exemplary gain andoffset estimation component can be further configured to perform atleast one of a least squares estimation or a correlation-basedestimation of the at least one of gain differences or offsetdifferences, as further described herein. In further embodiments, gainand offset estimation component can be further configured to estimatethe at least one of gain differences or offset differences on acontinuous basis to account for temperature variations, in anon-limiting aspect.

As a non-limiting example, an exemplary multipath digital audio combinercomponent can further comprise a multiplexing component configured toswitch from conveying one of one or more corrected digital audio signalsto conveying a second one of the one or more corrected digital audiosignals, wherein the multipath digital audio combiner component isfurther configured to perform gain and offset correction for the one ormore filtered digital audio signals to provide the one or more correcteddigital audio signals based at least in part on the gain determined bythe AGC component, as further described herein.

In still further non-limiting embodiments, exemplary multipath digitalaudio combiner component can be further configured to employ the offsetdifferences to adjust offset associated with the one or more scaleddigital audio signals, in another non-limiting aspect.

In still another non-limiting aspect, exemplary multipath digital audiocombiner component can be further configured to scale the one or morefiltered digital audio signals via one or more attenuation components toprovide one or more scaled digital audio signals based at least in parton the gain determined by the AGC component and at least one of the oneor more attenuation components. For instance, addition, in still furthernon-limiting embodiments, an exemplary multipath digital audio combinercomponent can be further configured to control the multiplexingcomponent to switch from conveying the one of the one or more correcteddigital audio signals to conveying the second one of the one or morecorrected digital audio signals based on at least one of a comparison ofthe characteristic measurement of the associated audio signal with a setof thresholds or a gain associated with the at least one of the one ormore attenuation components.

In addition, an exemplary multipath digital audio combiner component canbe further configured to control the multiplexing component to switchfrom conveying the one of the one or more corrected digital audiosignals to conveying the second one of the one or more corrected digitalaudio signals based on the characteristic measurement associated withsound pressure level based on at least one of amplitude measurement,absolute value of the amplitude measurement, or root-mean-square powermeasurement of digitized data associated with the one or more filtereddigital audio signals, in still further non-limiting embodiments. In afurther non-limiting aspect, exemplary embodiments can comprise amultipath digital audio combiner component that can be furtherconfigured to control the multiplexing component to switch fromconveying the one of the one or more corrected digital audio signals toconveying the second one of the one or more corrected digital audiosignals after a predetermined decay time based on the characteristicmeasurement.

In view of the subject matter described supra, methods that can beimplemented in accordance with the subject disclosure will be betterappreciated with reference to the flowchart of FIG. 9 . While forpurposes of simplicity of explanation, the methods are shown anddescribed as a series of blocks, it is to be understood and appreciatedthat such illustrations or corresponding descriptions are not limited bythe order of the blocks, as some blocks may occur in different ordersand/or concurrently with other blocks from what is depicted anddescribed herein. Any non-sequential, or branched, flow illustrated viaa flowchart should be understood to indicate that various otherbranches, flow paths, and orders of the blocks, can be implemented whichachieve the same or a similar result. Moreover, not all illustratedblocks may be required to implement the methods described hereinafter.

Exemplary Methods

FIG. 9 depicts an exemplary flowchart of non-limiting methods 1200associated with various non-limiting embodiments of the subjectdisclosure. For example, at 902, exemplary methods 900 can comprisegenerating one or more analog audio signals associated with one or moredigital audio signals having different scaling factors with one or moreamplifiers, in a non-limiting aspect. In another non-limiting example,at 904, exemplary methods 900 can comprise receiving the one or moredigital audio signals having different scale factors of an associatedaudio signal with one or more digital audio filters operatively coupledto one or more ADCs and configured to provide one or more filtereddigital audio signals, as further described herein. As a non-limitingexample, receiving the one or more digital audio signals with the one ormore digital audio filters can further comprise receiving the one ormore digital audio signals with one or more of one or more decimators orone or more low pass filters, as further described above.

In yet another non-limiting example, at 906, exemplary methods 900 cancomprise determining and adjusting gain for each of the one or moreamplifiers based on a characteristic measurement of the associated audiosignal with an AGC component, in a further non-limiting aspect. As anon-limiting example, the determining and the adjusting gain for each ofthe one or more amplifiers can further comprise determining andadjusting gain for each of the one or more amplifiers in predeterminedgain steps, as further described herein. For instance, determining andthe adjusting gain for each of the one or more amplifiers inpredetermined gain steps can further comprise determining and the adjustgain for each of the one or more amplifiers in predetermined gain stepscomprising a multiple of 6 dB gain steps.

As a further example, at 908, exemplary methods 900 can compriseestimating one or more of gain differences or offset differences betweenthe one or more filtered digital audio signals by a gain and offsetestimation component, in a non-limiting aspect. As a non-limitingexample, exemplary methods 900 can further comprise estimating one ormore of gain differences or offset differences by the gain and offsetestimation component via performing one or more of a least squaresestimation or a correlation-based estimation of the one or more of gaindifferences or offset differences, as further described herein. Inaddition, exemplary methods 900 can further comprise estimating the oneor more of gain differences or offset differences on a continuous basisto account for temperature variations, in a further non-limiting aspect.

In addition, exemplary methods 900 can comprise, at 910, performingoffset correction for the one or more filtered digital audio signals toprovide one or more corrected digital audio signals with a multipathdigital audio combiner component, in various embodiments describedherein.

At 912, exemplary methods 900 can comprise switching from conveying oneof one or more corrected digital audio signals to conveying a second oneof the one or more corrected digital audio signals, based on one or moreswitching criteria, in still further non-limiting aspects. For instance,switching based on one or more switching criteria can comprise switchingbased on one or more of a comparison of the characteristic measurementof the associated audio signal with a set of thresholds or a gainassociated with the one or more of the one or more attenuators. Inanother non-limiting example, switching based on the one or moreswitching criteria can further comprise switching based on one or moreof a comparison of the characteristic measurement of the associatedaudio signal with a set of thresholds or a gain associated with the oneor more of the one or more attenuators. In addition, in a furthernon-limiting aspect, switching based on the one or more switchingcriteria can comprise switching based on the characteristic measurementassociated with sound pressure level based on one or more of amplitudemeasurement, absolute value of the amplitude measurement, orroot-mean-square power measurement of digitized data associated with theone or more filtered digital audio signals, as further described herein.In another non-limiting aspect, switching based on the one or moreswitching criteria can further comprise switching after a predetermineddecay time based on the characteristic measurement.

In addition, exemplary methods 900 can further comprise, scaling the oneor more filtered digital audio signals via one or more attenuators toprovide one or more scaled digital audio signals based in part on thegain determined by the AGC component and one or more of the one or moreattenuators, still further non-limiting aspects.

What has been described above includes examples of the embodiments ofthe subject disclosure. It is, of course, not possible to describe everyconceivable combination of configurations, components, and/or methodsfor purposes of describing the claimed subject matter, but it is to beappreciated that many further combinations and permutations of thevarious embodiments are possible. Accordingly, the claimed subjectmatter is intended to embrace all such alterations, modifications, andvariations that fall within the spirit and scope of the appended claims.While specific embodiments and examples are described in subjectdisclosure for illustrative purposes, various modifications are possiblethat are considered within the scope of such embodiments and examples,as those skilled in the relevant art can recognize.

As used in this application, the terms “component,” “module,” “device”and “system” are intended to refer to a computer-related entity, eitherhardware, a combination of hardware and software, software, or softwarein execution. As one example, a component or module can be, but is notlimited to being, a process running on a processor, a processor orportion thereof, a hard disk drive, multiple storage drives (of opticaland/or magnetic storage medium), an object, an executable, a thread ofexecution, a program, and/or a computer. By way of illustration, both anapplication running on a server and the server can be a component ormodule. One or more components or modules scan reside within a processand/or thread of execution, and a component or module can be localizedon one computer or processor and/or distributed between two or morecomputers or processors.

As used herein, the term to “infer” or “inference” refer generally tothe process of reasoning about or inferring states of the system, and/orenvironment from a set of observations as captured via events, signals,and/or data. Inference can be employed to identify a specific context oraction, or can generate a probability distribution over states, forexample. The inference can be probabilistic—that is, the computation ofa probability distribution over states of interest based on aconsideration of data and events. Inference can also refer to techniquesemployed for composing higher-level events from a set of events and/ordata. Such inference results in the construction of new events oractions from a set of observed events and/or stored event data, whetheror not the events are correlated in close temporal proximity, andwhether the events and data come from one or several event and datasources.

In addition, the words “example” or “exemplary” is used herein to meanserving as an example, instance, or illustration. Any aspect or designdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects or designs. Rather, use ofthe word, “exemplary,” is intended to present concepts in a concretefashion. As used in this application, the term “or” is intended to meanan inclusive “or” rather than an exclusive “or”. That is, unlessspecified otherwise, or clear from context, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, ifX employs A; X employs B; or X employs both A and B, then “X employs Aor B” is satisfied under any of the foregoing instances. In addition,the articles “a” and “an” as used in this application and the appendedclaims should generally be construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform.

In addition, while an aspect may have been disclosed with respect toonly one of several embodiments, such feature may be combined with oneor more other features of the other embodiments as may be desired andadvantageous for any given or particular application. Furthermore, tothe extent that the terms “includes,” “including,” “has,” “contains,”variants thereof, and other similar words are used in either thedetailed description or the claims, these terms are intended to beinclusive in a manner similar to the term “comprising” as an opentransition word without precluding any additional or other elements.

What is claimed is:
 1. An apparatus, comprising: a gain and offsetestimation component configured to estimate at least one of gaindifferences or offset differences between a plurality of filtereddigital signals associated with a plurality of amplifiers; and amultipath digital signal combiner component configured to perform gainand offset correction for the plurality of filtered digital signals toprovide a plurality of corrected digital signals based at least in parton gain associated with each of the plurality of amplifiers.
 2. Theapparatus of claim 1, further comprising: an automatic gain control(AGC) component configured to determine and adjust the gain associatedwith each of a plurality of amplifiers based in part on a characteristicmeasurement of an associated input signal to at least one of theplurality of amplifiers.
 3. The apparatus of claim 2, wherein themultipath digital signal combiner component is further configured toscale the plurality of filtered digital signals via a plurality ofattenuation components to provide a plurality of scaled digital signalsbased at least in part on the gain determined by the AGC component andat least one of the plurality of attenuation components.
 4. Theapparatus of claim 3, wherein the multipath digital signal combinercomponent is further configured to facilitate switching from conveyingone of the plurality of corrected digital signals to conveying a secondone of the plurality of corrected digital signals based on at least oneof a comparison of the characteristic measurement of the associatedinput signal with a set of thresholds or a gain associated with the atleast one of the plurality of attenuation components.
 5. The apparatusof claim 4, wherein the multipath digital signal combiner component isfurther configured to facilitate switching from conveying the one of theplurality of corrected digital signals to conveying the second one ofthe plurality of corrected digital signals based on the characteristicmeasurement associated with a level of the associated input signal basedon at least one of amplitude measurement, absolute value of theamplitude measurement, or root-mean-square power measurement ofdigitized data associated with the plurality of filtered digitalsignals.
 6. The apparatus of claim 1, wherein the gain and offsetestimation component is further configured to perform at least one of aleast squares estimation or a correlation-based estimation of the atleast one of gain differences or offset differences.
 7. The apparatus ofclaim 1, wherein the gain and offset estimation component is furtherconfigured to estimate the at least one of gain differences or offsetdifferences on a continuous basis to account for temperature variations.8. The apparatus of claim 2, wherein the AGC component is furtherconfigured to adjust gain for each of the plurality of amplifiers inpredetermined gain steps.
 9. The apparatus of claim 8, wherein thepredetermined gain steps comprise a multiple of 6 deciBel (dB) gainsteps.
 10. An apparatus, comprising: a multipath digital signal combinercomponent configured to perform gain and offset correction for aplurality of filtered digital signals to provide a plurality ofcorrected digital signals, wherein the multipath digital signal combinercomponent is further configured to scale the plurality of filtereddigital signals via a plurality of attenuation components to provide aplurality of scaled digital signals based at least in part on gainassociated with a plurality of amplifiers and at least one of theplurality of attenuation components; and a multiplexing componentconfigured to switch from conveying one of the plurality of correcteddigital signals to conveying a second one of the plurality of correcteddigital signals.
 11. The apparatus of claim 10, further comprising: anautomatic gain control (AGC) component configured to determine andadjust the gain associated with each of the plurality of amplifiersbased in part on a characteristic measurement of an associated inputsignal to at least one of the plurality of amplifiers.
 12. The apparatusof claim 10, further comprising: a gain and offset estimation componentconfigured to estimate at least one of gain differences or offsetdifferences between the plurality of filtered digital signals associatedwith a plurality of digital filters.
 13. The apparatus of claim 12,wherein the gain and offset estimation component is further configuredto perform at least one of a least squares estimation or acorrelation-based estimation of the at least one of gain differences oroffset differences.
 14. The apparatus of claim 12, wherein the gain andoffset estimation component is further configured to estimate the atleast one of gain differences or offset differences on a continuousbasis to account for temperature variations.
 15. The apparatus of claim12, wherein the multipath digital signal combiner component is furtherconfigured to control the multiplexing component to switch fromconveying the one of the plurality of corrected digital signals toconveying the second one of the plurality of corrected digital signalsbased on at least one of a comparison of a characteristic measurement ofan input signal associated with the plurality of digital filters with aset of thresholds or a gain associated with the at least one of theplurality of attenuation components.
 16. The apparatus of claim 15,wherein the multipath digital signal combiner component is furtherconfigured to control the multiplexing component to switch fromconveying the one of the plurality of corrected digital signals toconveying the second one of the plurality of corrected digital signalsbased on the characteristic measurement associated with a level of theinput signal based on at least one of amplitude measurement, absolutevalue of the amplitude measurement, or root-mean-square powermeasurement of digitized data associated with the plurality of filtereddigital signals.
 17. The apparatus of claim 16, wherein the multipathdigital signal combiner component is further configured to control themultiplexing component to switch from conveying the one of the pluralityof corrected digital signals to conveying the second one of theplurality of corrected digital signals after a predetermined decay timebased on the characteristic measurement.
 18. The apparatus of claim 12,wherein the plurality of digital filters comprise at least one of aplurality of decimators or a plurality of low pass filters.